Note: Descriptions are shown in the official language in which they were submitted.
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SWITCH UNIT
BACKGROUND OF THE INVENTION
Technical Field
The present invention relates to a switch unit, and
particularly to a switch unit for preventing the generation of
noise at the time of a switching operation.
Related Art
There are various types of switch units used in
operation panels of various electronic devices, such as see
saw type switches that are a combination of a switch knob
having a fulcrum at a central section and a tact switch, and a
type that has a fulcrum at one end of a switch knob and is
operated at the other end. In particular, with the high
functionality and divergence of various devices in recent
years, switches with an automatic reset function, where a
switch knob returns to its original position after the switch
has been operated and a hand removed, are being widely used.
This type of conventional switch unit will be described
using Fig. 6, Fig. 7 and Fig. 8. Fig. 6 is an upper external
view of a conventional switch unit. Fig. 7 is a cross
sectional view of the switch unit shown in Fig. 6 taken along
line D - D, and shows a stationary state where the switch is
not operated. Fig. 8 is a cross sectional view of the switch
unit shown in Fig. 6 taken along line D - D, and shows an
operation state where the switch has been operated. These
drawings show examples of a see-saw type switch unit.
The conventional switch unit is provided with a switch
knob 12 capable of being tilted with a rotational shaft 11 in
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a switch housing 10 as a center, and a switch operation is
carried out by the switch operator pressing the upper surface
of this switch knob. The switch operator performs ON and OFF
operations of the switch unit by pressing close to the two
ends of the switch knob 12, but a projection 13 is formed on a
rear side of the section on the switch knob 12 pressed by the
switch operator. This projection 13 is provided in order to
supply pressing force to a resin type tact switch 15 fixed to
a printed substrate 14, and this pressing force is exerted via
a switch shaft 16 arranged by the tip of the projection 13.
The switch shaft 16 has movement in the lateral direction
regulated by a guide rail 17, and it is possible to always
exert pressing force in a direction vertical with respect to
the tact switch 15.
The tact switch 15 merely transmits an electrical signal
to an ON/OFF hold circuit, not shown, in response to pressure
from the switch operator, and the ON/OFF hold circuit (not
shown) carries out switch turnover/detent. In this way,
electrical signals are transmitted to an electronic device
(not shown) etc. connected to the switch unit, and it is
possible to carry out ON/OFF switching.
If the switch knob 12 is operated by a switch operator,
the switch unit is put into a state as shown in Fig. 8, but
when the operator releases the switch knob 12, the switch knob
12 will immediately return to the original position shown in
Fig. 7. This automatic reset function is well known in the
related art, and so detailed description will be omitted, but
uses, for example, restoration force of a flexible switch
(refer to Japanese Patent Laid-open Publication No. Hei 11-
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86683 for example), or causes restoration to an original
position by providing a spring at a connecting section of a
rotational shaft 11 and the switch knob 12 and utilizing
resilient force of this spring.
However, with the above described switch unit of the
related art, there is a problem in that when the switch knob
12 is restored to the original position, noise is generated as
a result of the tip of the projection 13 hitting the switch
shaft 16. In order to solve this problem, it has been
considered to adopt a switch unit using a push-pull switch
such as that disclosed in Japanese Patent Laid-open
Publication No. Hei 11-86683, but it is necessary to change
the structure of the switch unit significantly, and is not a
realistic solution because it causes increase in cost.
The present invention is intended to solve the above
described problems, and an object of the present invention is
to provide a switch unit that does not significantly change a
switch structure, suppresses striking noise generation and has
a quiet operating sound.
SUMMARY OF THE INVENTION
In order to solve the above described problems, a switch
unit of the present invention comprises a switch knob arranged
capable of being tilted with a rotational shaft as a shaft
center and provided with an automatic reset function for
restoring to an original position, a switch shaft connection
shaft provided on the switch knob, a switch shaft being moved
in accordance with an inclination restoration operation as a
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result of connecting to the switch shaft connection shaft, a
guide rail for guiding movement of the switch shaft in a
straight line, and a tact switch, arranged capable of
connection and disconnection to and from the switch shaft, for
electrical connection and disconnection as a result of
pressure from the switch shaft, wherein the tact switch has a
region pressed from the switch shaft constituted by a
resilient member.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is an upper external
view of a switch unit
of an
embodiment of the present invention.
Fig. 2 is a cross sectional view of the switch unit
shown in g. 1 taken along line A A, and shows a stationary
Fi -
state where th e switch knob is not
operated.
Fig. 3 is a cross sectional view of the switch unit
shown in Fi g. 1 taken along line A A, and shows an operation
-
state where th e switch knob has been operated.
Fig. 4A is an upper external iew of a switch
v unit of an
embodiment of the present invention.
Fig. 4B shows a cross section along line - B in Fig.
B
4A.
Fig. 5A is an upper external view of a switch unit of
the related art.
Fig. 5B shows a cross section along line C - C in Fig.
5A.
Fig. 6 is an upper external view of a conventional
switch unit.
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Fig. 7 is a cross sectional view of the switch unit
shown in Fig. 6 taken along line D - D, and shows a stationary
state where the switch knob is not operated.
Fig. 8 is a cross sectional view of the switch unit
shown in Fig. 6 taken along line D - D, and shows an operation
state where the switch knob has been operated.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of the present invention will now
be described using the attached the drawings. Fig. 1 is an
upper external view of a switch unit of an embodiment of the
present invention, Fig. 2 is a cross sectional view of the
switch unit shown in Fig. 1 taken along line A - A showing a
stationary state where the switch knob is not operated, and
Fig. 3 is a cross sectional view of the switch unit shown in
Fig. 1 taken along line A - A showing an operation state where
the switch knob has been operated. The same reference numerals
are assigned to parts that are the same as or analogous to
those parts shown in the related art described above.
As will be clear from Fig, 2 and Fig. 3, the
characteristic feature of this embodiment is that a switch
knob 22 and a switch shaft 26 are connected. Describing this
connection structure in detail, a projection 23 for shaft
connection is formed on the switch knob 22 at the same
position as the projection 13 shown in the related art (refer
to Fig. 7 and Fig. 8) , and a switch shaft connection shaft 24
is formed on this shaft connection projection 23. The switch
shaft 26 becomes capable of being moved in accordance with an
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inclination restoration operation of the switch knob 22, by
being connected to the switch shaft connection shaft 24. Also,
a guide rail 17 is arranged to the Left and right of the
switch shaft 26, and the switch shaft 26 is moved in a
straight line with movement in the left and right direction
being regulated by the guide rail 17. Accordingly, it is
possible to always have pressing force exerted in a vertical
direction with respect to the tact switch 25.
With the above described structure, that is, by
connecting the switch knob 22 and the switch shaft 26, it is
possible to prevent the generation of striking noise generated
in the related art switch unit due to clashing of the switch
knob 12 and the switch shaft 16. Here, if the structure of the
switch unit of this embodiment is adopted, there is clashing
of the switch shaft 26 and the tact switch 25, but with this
embodiment, in order to prevent the striking noise due to
clashing of the switch shaft 26 and the tact switch 25, a
section where the tact switch 25 is pressed from the switch
shaft 26 is made of a resilient member. Accordingly, striking
noise is not generated even if the switch shaft 26 strikes the
tact switch 25, and it is possible to provide a switch unit
which is quiet at the time of switch operation. It is possible
to use a well known resilient member such as rubber or
silicone rubber as the resilient member used in the tact
switch 25.
Also, as a preferred operation of this embodiment, there
is the advantage that shaking of the switch knob 22 is reduced
compared to the switch unit of the related art. By reducing
this shaking, there is the effect of improving feeling at the
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time of switch operation compared to the switch unit of the
related art. This point will be described using Fig. 4A, Fig.
4B, Fig. 5A and Fig. 5B. Here, Fig. 4A is an upper external
view of a switch unit of an embodiment of the present
S invention, while Fig. 4B shows a cross section along line B -
B in Fig. 4A. Fig. 5A is an upper external view of a switch
unit of the related art, with Fig. 5B showing a cross section
along line C - C in Fig. 5A.
With the related art switch unit shown in Fig. 5A and
Fig. 5B, the switch knob 12 is only supported by a rotation
shaft 11 formed in the switch housing 10 and a bearing surface
12a provided on the switch knob 12. Therefore, the switch knob
12 of the related art has the disadvantage of mechanically
shaking in the direction of the arrow (X) shown in Fig. 5 (A) .
In order to stop this shaking, it has been considered to widen
the surface area of the bearing surface 12a, but with this
method, the sliding resistance between the rotation shaft 11
and the bearing surface 12a is increased, which reduces the
feeling of the switch operation, and it is difficult to
prevent shaking with the structure of the related art.
On the other hand, according to the switch unit of this
embodiment shown in Fig. 4A and Fig. 4B, the switch knob 22 is
connected to the switch shaft 26, and also the switch shaft 26
has movement in the lateral direction regulated by the guide
rail 17, which means that a structure is obtained that makes
it difficult for shaking to occur. Therefore, according to
this embodiment, it is possible to provide a switch unit which
prevents shaking of the switch knob 22, and which also
improves feeling at the time of switch operation.
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In Fig. 4B, there are two shaft connection projections
23 provided, on either side of the switch shaft 26, but it is
possible to prevent shaking of the switch knob 22 if only one
of them is provided.
Also, with this embodiment, description has been given
with a see-saw type switch unit as an example, but it is also
possible to apply the switch unit to any type of switch, such
as a switch knob that has a fulcrum at one end and is operated
by the other end, or a switch unit where the switch knob can
be inverted in a number of directions.
As has been described above, according to the present
invention, it is possible to provide a switch unit that
suppresses striking noise without significantly changing the
switch structure, and which is quiet when operated.
Also, by connecting the switch knob to the switch shaft,
it is possible to prevent the switch knob shaking, which means
that it is possible to provide a switch unit with improved
feeling at the time of operation.
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